The present invention relates to a waterproof structure of a connector, and more specifically, to a waterproof structure that improves sealing ability between a connector formed of a synthetic resin and a sheathed electric wire that is to be connected to the connector.
This kind of waterproof structure of a connector is shown in FIG. 6. As shown in the same figure, a connector 1 comprises a connector body 2 and a cover 3 both formed of a synthetic resin, and constructed in such a manner that the sheathed electric wire 4 is connected to and disposed on the connector body 2 and covered by the cover 3.
The connector body 2 comprises a connection housing 5 including connecting terminal fittings (not shown) integrated therein, a wire leading part 6 extending from the connection housing 5. The wire leading part 6 includes a plurality of partition walls 7 along the direction in which the sheathed electric wires 4 extend, and between adjacent partition walls 7, there are provided wire receiving grooves 8 where the sheathed electric wires are disposed.
In order to connect and fix the sheathed electric wire 4 to the connector, as shown in FIG. 6, a tubular waterproof member 9 having compatibility with a synthetic resin which forms the wire leading part 6 under melted condition is fitted onto the periphery of the sheathed electric wire 4, and then the sheathed electric wire 4 is heated under the condition being received in the wire leading part 6 to melt and fuse the waterproof member 9 and the resin cover of the sheathed electric wire 4 together, as well as the waterproof member 9 and the wire leading member 6 together. The portions between cover 3 and the waterproof member 9, and between cover 3 and the wire leading part 6 are also heated to be fused into a whole. An ultrasonic excitation is utilized for the heating operation.
In the related waterproof structure of a connector as described above, the resin material forming the wire leading part 6 of the connector body 2 and the cover is normally different from that forming the cover of the sheathed electric wire 4 because the flexibility or other physical properties required for the sheathed electric wire 4 differs from the physical property required for the connector 1. Therefore, in order to achieve compatibility between the material forming the wire leading part 6 of the connector body 2 and/or the cover and that forming the sheathed electric wire 4, the waterproof member 9 is required to be fitted on the outer periphery of the sheathed electric wire 4. However, there has been a recognized disadvantage that it requires many working processes because the respective sheathed electric wires 4 had to be fitted with the waterproof members 9 at prescribed portions in the vicinity of their terminal portion before the sheathed electric wire 4 is connected to the connector 1.
In the related waterproof structure of a connector as mentioned above, while the cross sectional configuration of the wire receiving groove 8 formed between adjacent partition walls 7 is rectangular, the cross sectional configuration of the sheathed electric wire 4 fitted with the waterproof member 9 is circular. Therefore, the contact between the wire leading part 6 and the waterproof member 9 and the contact between the cover 3 and the waterproof member 9 may not be uniform and thus the waterproof member 9 may not be brought into intimate contact with the wire leading part 6 and/or the cover 3 even after they are heated and melted. As a result, a clearance may be formed between them due to insufficient fusion, and in some circumstances, it may lead to loss of waterproof ability.
It is therefore an object of the present invention is to provide a waterproof structure of a connector wherein the fitting operation is quite easy and the sealing ability between the sheathed electric wire and the connector housing is enhanced.
In order to achieve the above object, according to the present invention, there is provided a waterproof structure of a connector comprising:
at least one electric wire covered by a resin sheath; and
a connector body including:
a connecting part to which one end portion of the sheathed electric wire is connected; and
a wire leading part made of a resin material and having a wire receiving groove for receiving the sheathed electric wire connected to the connecting part, the wire receiving groove having a cross sectional shape substantially identical with a cross sectional shape of the sheathed electric wire so that the inner surface of the wire receiving groove and the outer surface of the sheathed wire is to be heat-welded.
According to the above configuration, the resin sheath of the sheathed electric wire is brought into intimate contact with the inner surface of the wire receiving groove. By heat-welding them in this state, the resin material of the wire leading part and the resin sheath of the sheathed electric wire are fused to establish a satisfactory waterproof structure without forming a clearance between the wire receiving groove and the sheathed electric wire.
Preferably, the resin sheath integrally covers at least one end portions of a plurality of electric wires.
According to the above configuration, it is not necessary to form partition walls to isolate respective sheathed electric wires in the wire receiving groove of the wire leading part, the space required for mounting the sheathed electric wire may be reduced. Therefore, according to the second aspect of the present invention, the connector body may be miniaturized.
Preferably, the resin sheath is made of a thermoplastic elastomer.
According to the above configuration, it exhibits plasticity as heat is added and easily welded to the resin material to form the wire leading part.
Preferably, the thermoplastic elastomer is a copolymer including a resin material forming the wire leading part as a polymerized ingredient.
According to the above configuration, chemical structure of the resin material used for the wire leading part and that used for the resin sheath are similar, and thus fusibility between these members may be enhanced during heat welding so as to obtain a strong connection.
Preferably, the connector body includes a cover body having a shape being brought into an intimate contact with the sheathed electric wire received in the wire receiving groove. The cover body is made of a resin material having compatibility with the resin material of the wire leading part to be heat-welded with the sheathed electric wire and the wire leading part.
According to the above configuration, it ensures fusion among the cover body, the wire leading part, and the resin sheath of the sheathed electric wire by heat welding so that the waterproof ability is further enhanced.
Preferably, the wire leading part, the sheathed wire and the cover body are heat-welded by applying frictional heat energy generated by ultrasonic excitation.
According to the above configuration, an uniform frictional heat energy is generated between itself and adjacent member when ultrasonic excitation is applied, so that an uniform heat welding may be accomplished. Therefore, the waterproof ability of the connector is enhanced without generating any clearance between members.